The invention relates to a static mixer, to an apparatus comprising a mixer of this kind and to a use of the mixer.
Static mixers for mixing at least two flowable components which are compact and which in spite of a simple, material-saving construction of their mixer structure yield good mixing results are described in EP-A-0 749 776 and EP-A-0 815 929. These mixers are suitable for mixing highly viscous substances such as for example sealing masses, two-component foams or two-component adhesive bonders. They can be economically manufactured of thermoplastics through injection molding so that they can be economically applied for a throw-away use. A xe2x80x9cthrow-away mixerxe2x80x9d of this kind is mainly used for products which harden, since for these products the mixer cannot practically be cleaned.
The mixing results of the referenced mixers are insufficient in certain applications, in particular in cases in which components are mixed which have different viscosity values. An insufficient mixing result becomes evident in that at least one flow filament which consists of only one of the components to be mixed passes through the mixer structure and in so doing experiences practically no or too slow a mixing with adjacent flow filaments. A flow filament of this kind is designated here as xe2x80x9cmix-resistantxe2x80x9d. Mix-resistant flow filaments arise above all in static mixers in which the mixer structure consists of a periodic succession of similar elementary mixing chambers. But mix-resistant flow filaments can also be observed in non-periodic mixer structures.
It is an object of the invention to create a static mixer of which the mixing result is improved in comparison with the known mixers. This object is satisfied by the static mixer which is described herein.
The static mixer comprises a plurality of mixing chambers which form a mixer structure. The mixing chambers are arranged one behind the other as well as adjacently in a tube along a tube axis. They can be used for mixing at least two flowable components. The mixer structure represents a modification of a basic structure. In said basic structure the mixing chambers are separated from one another by radial walls which are oriented in the direction of the tube axis and by walls which are transverse to the tube axis. Apertures between adjacent chambers in the radial walls form inputs and outputs for the components to be mixed. The modification consists of structure changes at individual locations of the basic structure. It is carried out in such a manner that a transverse dislocation of mix-resistant flow filaments results in the flowing components being mixed, with these flow filaments being mix-resistant with respect to the basic structure.
Through the transverse dislocation of the mix-resistant flow filament the latter enters into a region in which it is subject to a strong deformation and thereby becomes more miscible. The dislocated flow filament is replaced by another one which is now in turn largely decoupled from the mixing process. It is therefore advantageous if such disturbance locations, which cause a dislocation of the respective mix-resistant flow filament, are set up at a plurality of positions of the static mixer. It is also advantageous if the disturbance locations are formed differently.
The disturbance locations as a rule have a disadvantageous effect on the mixing process in flow regions which lie outside the mix-resistant flow filament. If this is the case, then only as many disturbance locations should be provided as are necessary for a sufficient number of dislocations of the mix-resistant flow filaments.
The disturbance locations can be formed such that they do not act directly on the mix-resistant flow filament, but rather indirectly in that they cause deflections in their direct region of influence which then in turn influence the mix-resistant flow filament. A design of suitable disturbance locations can be found empirically. Experiments with components which are to be mixed and which are differently colored are carried out and the results for a basic structure are compared with those of a modification of the basic structure, with it being possible to determine whether mix-resistant flow filaments have actually been dislocated.
The following sections describe advantageous embodiments of the static mixer in accordance with the invention, apparatuses with mixers of this kind, and a use thereof.